Oral device

ABSTRACT

An oral device for use with a person in which at least one non-toxic gas pulse is delivered to a predetermined location in the mouth via a device conduit. The oral device may be provided as a kit with at least one device for measuring the subject&#39;s responses and representing them as feedback to the subject/clinician. A method of creating a gas bolus pulse train, delivering it to a predetermined mouth area, and monitoring the subject&#39;s responses to it, is also shown. The oral device and method may be used as a diagnostic tool, or a therapeutic tool, in swallowing or speech rehabilitation of children and adults who have swallowing, speech, salivary, and/or oral sensorimotor impairments.

CROSS REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation of prior U.S. application Ser. No.13/013,509, filed Jan. 25, 2011, which is a continuation of U.S.application Ser. No. 11/411,241, filed Apr. 26, 2006, which claims thebenefit of U.S. provisional patent application No. 60/676,942, filed May3, 2005, the entire disclosures of which are hereby incorporated hereinby reference.

FIELD OF THE INVENTION

This invention relates to oral devices and in particular an oral devicethat may be used as a diagnostic device, or to evoke swallowing, or inother therapeutic oral applications.

BACKGROUND OF THE INVENTION

Swallowing is a complex behaviour in which the output of an integrativebrainstem network gives rise to a patterned movement sequence describedas the pharyngeal stage of swallowing. While several lines of evidencehave demonstrated the importance of oropharyngeal sensory inputs inactivating this medullary swallowing network, the range of afferentpatterns that are both necessary and sufficient to evoke swallowing hasnot been fully elucidated. Stimulation of receptive fields innervated bythe superior laryngeal nerve (SLN) or the pharyngeal branch of theglossopharyngeal nerve (GPNph) appear to be particularly effective inevoking or modulating the pharyngeal swallow; these “reflexogenic” areascorrespond to the laryngeal mucosa, including the epiglottis andarytenoids, the lateral pharyngeal wall, posterior tonsillar pillar andperitonsillar areas.

In humans, the anterior faucial pillar historically has been consideredthe most reflexogenic site for swallowing. However, the recent findingthat the pharyngeal swallow may begin after the bolus head passes theanterior faucial pillars in healthy adults, including geriatric adults,suggests that stimulation of more posterior pharyngeal regions may berequired to elicit swallowing. The importance of more posteriororopharyngeal areas in swallowing elicitation is also suggested byanatomic evidence that the human posterior tonsillar pillar, as well asdiscrete regions of the palate, pharynx and epiglottis are innervated bya dense plexus formed from the GPNph and the vagus nerve. The spatialcorrespondence between these areas of dual vagal/GPNph innervation andreflexogenic areas for swallowing has lead to the hypothesis thatswallowing is elicited most readily by stimulation of areas innervatedby both the GPNph and vagus. Dynamic stimuli that excite primaryafferents within a number of receptive fields over time appear to elicitswallowing more readily than do static stimuli.

A variety of stimulus modalities have been applied in attempts to evokeswallowing. Repetitive electrical stimulation of the SLN or the GPN,particularly at stimulation frequencies between 30 and 50 Hz, evokesswallowing in a number of animal species. This suggests that therepetitive nature of the stimulus, and the repetition rate, are criticalvariables in swallowing elicitation. More recently, electricalstimulation of the pharynx has been reported to increase both theexcitability and size of the pharyngeal motor cortex representation inhumans, and facilitate swallowing in dysphagic patients followingstroke. Mechanical and chemical stimuli can evoke swallowing in animalspecies. In humans, reports on the effects of cold mechanicalstimulation of the anterior tonsillar pillar have been variable, someauthors reporting decreases in swallowing latency and increases inswallowing frequency, and others failing to find an effect of this typeof stimulation on oropharyngeal bolus transit, esophageal coordination,or the temporal pattern of swallowing. Three studies have examined theeffects of cold mechanical stimulation applied to the anterior tonsillarpillars in small samples of dysphagic stroke patients. They reported ashort-term facilitation of swallowing, measured in terms of reduceddelay of the pharyngeal swallow, in some patients, with no relatedreduction in aspiration. Longitudinal studies, examining the potentiallong-term effects of oropharyngeal sensitisation on not only swallowingphysiology but also on nutritional and respiratory health, have not beenreported. Reports on the effects of gustatory stimuli also have beenvariable. A sour bolus has been reported to facilitate swallowing instroke patients. Whereas some authors have reported that swallowinglatency is significantly reduced by a combination of mechanical, cold,and gustatory (sour) stimulation, others have reported that a cold plussour bolus reduces the speed of swallowing.

Prior art research shows a novel method for determininglaryngopharyngeal sensory thresholds using trains of discrete air pulsesdelivered endoscopically to the mucosa of the pyriform sinuses andaryepiglottic folds. Sensory thresholds are calculated throughpsychophysical testing and from elicitation of the laryngeal adductionreflex. The air-pulse train is an interesting stimulus in that it hasmany of the properties that appear crucial in evoking the pharyngealswallow. For example, a single air pulse is a dynamic stimulus thatcould be applied to a number of receptive fields including regionsinnervated by both the GPNph and SLN. Furthermore, an air-pulse trainrepresents a repetitive stimulus that can be applied at specificfrequencies and pressures.

Accordingly, it would be advantageous to provide an oral device that candeliver air-pulse trains to the oral, oropharyngeal or peritonsillarareas. Further it would be advantageous to provide an oral device thatfacilitates and/or elicits swallowing in adults and children. As well,it would be advantageous to provide an oral device that can providevisual and/or audio feedback responsive to a swallowing attempt. Inaddition, it would be advantageous to provide an oral device that may beused to improve the motor integrity (e.g., strength, control, tone,accuracy) of the lips, tongue, and/or soft palate, with associatedimprovements in swallowing, as well as speech production and speechintelligibility.

In addition, recent studies have suggested that the air-pulse traindelivered to the oral or oropharyngeal areas results in laryngealelevation, in some cases associated with a swallow proper. Thus, iswould be advantageous to provide an oral device that facilitates orevokes laryngeal movements, such as elevation movements, since laryngealmovement may be a precursor to a swallow proper. It is also clear fromprevious studies that delivery of an air bolus into the mouth is not theonly way in which laryngeal elevation can be achieved. A well-knowntherapeutic maneuver in swallowing rehabilitation is the ‘effortfulswallow’ in which the patient is simply instructed to swalloweffortfully by contracting his/her muscles maximally. This has beenshown to result in a more efficient, safer swallow. It has recently beenshown that an effortful swallow is associated with increased laryngealmovement. This laryngeal movement can be recorded from a transducer wornaround the neck. The amplitude of the output signal from the laryngealtransducer, representing laryngeal movement, is significantly greater inassociation with an “effortful” swallow, compared to a normal swallow.Other therapeutic maneuvers that also result in increased laryngealmovement include the Mendelsohn Maneuver, supraglottic swallow,super-supraglottic swallow, and the Shaker exercise.

Accordingly it would be advantageous to provide a feedback system thatcan provide the patient and clinician information about the physiologiccorrelates of these compensatory swallowing maneuvers, and similarmaneuvers that produce laryngeal movement patterns. Certain speechexercises also give rise to laryngeal movement. For example, thepharyngeal squeeze involves producing a vowel sound at a high pitch.This elevates the larynx while at the same time maximally recruiting thepharyngeal muscles. Thus, it is used to strengthen the pharyngealmusculature. Accordingly, it would be advantageous to provide a feedbacksystem that could provide information to the patient and clinician aboutthe laryngeal movement associated with these speech therapy exercises.

SUMMARY OF THE INVENTION

The present invention is an oral device for use with a subject inhis/her mouth. The oral device includes at least one conduit fordelivering a human non-toxic gas to a predetermined location in thesubject's mouth. There is a means for positioning the conduit in thesubject's mouth and a means for generating at least one gas pulsethrough the conduit.

In another aspect of the invention there is provided an oral kit forcreating a gas bolus in a subject and monitoring predetermined physicalresponses. The oral kit includes a means for producing a gas bolus in asubject's mouth; at least one measuring device for measuring thesubject's physical responses; and a control system operably connected tothe at least one measuring device, the control system having a storingdevice for storing the measurements from the measuring device.

In a further aspect of the invention there is provided a method ofcreating a gas bolus in a subject's mouth comprising the step ofdelivering a gas pulse train to a predetermined area in the subject'smouth.

In a still further aspect of the invention there is provided a method ofdiagnosing oral sensory abnormality in a subject comprising the step ofdelivering at least one gas pulse of predetermined amplitude andduration to a predetermined location within the subject's mouth andmonitoring the response.

Further features of the invention will be described or will becomeapparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an oral device constructed in accordancewith the present invention and shown above a dental impression;

FIG. 2 is an enlarged perspective view of the exit portion of the oraldevice of FIG. 1;

FIG. 3 is a perspective view of the oral device of FIG. 1 shown on adental impression and shown with an air pulse;

FIG. 4 is a perspective view of an alternate embodiment of the oraldevice of the present invention and showing a plurality of exit holes;

FIG. 5 is a front view of a mouth with the oral device of the presentinvention positioned therein and showing the air-pulse delivery in theperitonsillar region;

FIG. 6 is a front view of a mouth with the oral device of the presentinvention positioned therein similar to that shown in FIG. 5 but showingan alternate location of the air-pulse stimulation delivery, namely thetongue; and

FIG. 7 is a front view of a mouth with the oral device of the presentinvention positioned therein similar to that shown in FIGS. 5 and 6 butshowing an alternate location of the air-pulse stimulation deliverynamely, the roof of the mouth or palate.

FIG. 8 is a perspective view of a subject in a regular chair using theoral kit of the present invention;

FIG. 9 is a perspective view of the oral kit of present invention whichis similar to that shown in FIG. 8 but showing that the device of thepresent invention may also be used with an older subject in a wheelchair;

FIG. 10 is a perspective view of the oral device of the presentinvention showing a hand held air pulse device;

FIG. 11 is a front view of the control system of the oral kit of thepresent invention;

FIG. 12 is a graph showing the laryngeal and respiratory response frombilateral oropharyngeal stimulation;

FIG. 13 is a graph showing the laryngeal and respiratory response tohand stimulation;

FIG. 14 is a graphical representation of the experimental paradigmshowing four air pulse periods between two baseline periods;

FIG. 15 is a graph showing time course of output of laryngeal bellowspositioned around the neck over the thyroid cartilage for Subject 1 andSubject 2;

FIG. 16 is a bar graph showing mean number of swallows produced during5-minute baseline period and 5-minute stimulation conditions; and

FIG. 17 is bar graph showing mean number of swallows produced during5-minute baseline period and 5-minute air-pulse stimulation conditionswith a subject who had had a stroke.

DETAILED DESCRIPTION OF THE INVENTION Splint Fabrication

Referring to FIGS. 1 to 3, the oral device of the present invention isshown generally at 10. The oral device or splint 10 includes a lowerdental splint 12 and a means for delivering a gas pulse to apredetermined region in the mouth. The gas pulse delivery means includesat least one conduit or tube 14 having at least one opening 16 at theend thereof positioned such that gas is delivered to a predeterminedregion in the mouth. Preferably there are two tubes 14 thereby allowingfor unilateral stimulation on the left side or the right side of thesubject as desired.

The splint or oral device 10 provides a means of delivering air or gaspulse trains to the peritonsillar region. As well it can be used todeliver air or gas pulse trains to other regions in the mouth. The oraldevice 10 is preferably made of dental resin that is molded over adental impression cast 20. Because of a potential effect of jaw openingon the threshold for evoked swallowing, the thickness of the splint 10is designed to fall within the just-noticeable-difference (JND) for jawposition (i.e., 1-2 mm). Preferably, polyethylene tubing (inner diameter(ID): 1.14 mm, outer diameter (OD): 1.57 mm) attached via silicone tothe inferior border of the splint 10 lateral to the alveolar ridge ofthe mandible and extended approximately 0.1 cm to 1 cm past theposterior edge of the dental splint 10. Optimally, the rigidpolyethylene tubing is terminated with human implant grade silicone.Preferably, a 1.5 mm diameter circular opening 16 is formed in thelateral wall of the terminating tubing 14. Opening 16 directs the air orgas pulse trains toward the peritonsillar region of the lateraloropharynx as shown in FIG. 5. Alternatively the air or gas trains canbe directed to the tongue as shown in FIG. 6 or the roof of the mouth asshown in FIG. 7. The left and right sides of the splint 10 are fittedwith separate tubes 14 to allow for unilateral stimulation conditions.Anteriorly, the tubes 14 from the right and left sides exit the splint12 within 1 cm of the subject's midline, pass between the subject'slips, are connected to larger diameter polyethylene tubing (preferably1/16 inch to ⅛ inch inner diameter) and then are connected to aY-connector 24. The air-pulse trains are generated either (1) manuallyby the experimenter or user as shown in FIG. 10, or (2) by aelectropneumatic control system (see below). Referring to FIG. 10, forthe case of manual control, the right and left tubing 14 are connectedwith a Y-connector 24. Tubing 26 runs from the Y-connector 24 to an airbulb 28 that is manually operated by the experimenter or the subject.The oral device of the present invention may be modified in a number ofdifferent ways. For example, as shown in FIG. 4, the oral device orsplint 30 may include a plurality of holes 32. The holes 32 arepositioned around the splint such that gas or air is pulsed at differentlocations in the mouth.

FIGS. 5, 6 and 7 show different versions of the oral device at 10, 40and 44 respectively. As can be seen in the figures the position of theholes 16, 42 and 46 can be arranged such that the air or gas is pulsedonto different locations in the mouth. FIG. 5 shows the pulses directedto the peritonsillar region, FIG. 6 shows the pulses directed to thetongue and FIG. 7 shows the pulses directed to the roof of the mouth. Itwill be appreciated by those skilled in the art that these regions asshown by way of example only and that the pulses may be directed to avariety of different regions. As discussed above, the utility of theoral device of the present invention may be enhanced by providingfeedback in regard to a number of physical responses of the subject. Forexample by monitoring the laryngeal movement, a swallow may beindicated. In addition, the nature of the swallow may be indicated, suchas a weak, or stronger, or satisfactory swallow. An effortful swallowalso may be indicated. A central processor connected with a monitor orspeaker may be used for visual or auditory feedback to a patient andclinician regarding laryngeal elevation. Within the central processor,the output signals can be compared to preset threshold values such thata correct response signal (visual or auditory) is delivered to thepatient if their swallowing behaviour has surpassed some threshold levelset by the clinician/caregiver.

The oral device 10, 30 of the present invention may be used inconjunction with a control system 50 as shown in FIG. 11. The controlsystem 50 controls the air pulse parameters, specifically the pressure52, the duration 54 and the frequency 56. In most cases the pulsefrequency is in a range from 0.5 to 30 Hz, the pulse train is in a rangefrom 2 and 20 seconds and the pressure is in a range from 3 cm to 15 cmwater. In general the gas is air and it is at ambient temperature.

The control system may also be operably connected to other devices whichprovide useful feedback when the oral device is used eithertherapeutically or diagnostically. Preferably the control system alsoincludes feedback from monitoring or measuring devices that measuremeasurable physical responses. Specifically the control system may beattached to a chest (respiratory) movement sensor 58, a laryngealmovement sensor 60, an accelerometer 62 and/or a pulse oximeter 64 allshown in FIGS. 9 and 10. The chest movement sensor 58 or respiratorymovement transducer is for monitoring or measuring the respiratory cycleand periods of swallow-related apnea. The laryngeal movement transduceror sensor 60 is for monitoring or measuring laryngeal elevation/movementassociated with swallowing. The accelerometer or throat microphone 62 isfor monitoring or measuring the sounds of swallowing. The pulse oximeter64 is for monitoring the blood oxygen level. Swallowing and trachealaspiration of ingested material can be associated with decreased bloodoxygen saturation. Therefore, it is advantageous for the oral device andkit to include a means of monitoring oxygen saturation of the blood. Theoutputs from these devices are fed into a central processor or controlsystem 50 and then displayed visually on a monitor 66, or acousticallyas auditory feedback via a speaker. Within the central processor, theoutput signals can be compared to preset threshold values such that acorrect response signal (visual or auditory) is delivered to the patientif their swallowing, or oral motor behaviour, has surpassed somethreshold level set by the clinician/caregiver. The output signal fromthe laryngeal movement sensor 60 is displayed as a time course ofmovement amplitude over time, providing the patient information onlaryngeal movement associated with swallowing. This can be used asfeedback with respect to swallowing strength, swallowing duration, andtherapeutic maneuvers, such as the effortful swallow. It will alsoindicate the association in time between delivery of air pulses, andassociated swallowing responses. This serves not only to enhancelearning for the patient, but also to inform the clinician/caregiverregarding the efficacy of air-pulse therapy for an individual patient.The output signal from the respiratory transducer 58 is used in asimilar manner, providing both the patient and clinician information onthe effects of the air pulses on the respiratory cycles, the associationbetween respiration and swallowing, including coordination of the“swallowing apnea” within the inspiratory and expiratory phases of therespiratory cycle. The signal from the accelerometer 62 provides anothermeans of identifying swallowing—it is a highly “swallow specific”signal, associated with movement of the ingested bolus through the uppersphincter of the esophagus. Thus, when combined with the laryngeal andrespiratory signals, it provides a feedback environment for the patientand clinical that is very sensitive and specific to swallowing events.Thus, swallows (in response to air pulse application) can bedistinguished from oral movements such as tongue movement for example.The oral device of the present invention could be sold separately or asa kit in conjunction with the control system 50 and one or more of thefeedback devices.

The kit could also be used as a patient safety monitoring system.Studies have shown that swallowing accompanied by tracheal aspiration isassociated with a greater-than 2% decrease in blood oxygen saturation(see above). Further, some swallowing therapies that involve “bearingdown exercises” are associated with cardiac arrythmias in patients witha history of stroke. Therefore, the oral kit of the present inventionincludes a patient safety-monitoring component that monitors both bloodoxygen (with a blood oxygen saturation probe that is worn on the finger)(not shown), and pulse monitor or pulse oximeter 64, and a respirationmonitor or chest movement sensor 58. These signals provide the clinicianand patient ongoing information about patient safety duringtherapy/practice sessions.

It will be appreciated by those skilled in the art that there may be anumber of ways that the kit of the present invention may be used. It maybe used by a subject who can move around easily and can use a regularchair as shown in FIG. 8. Alternatively it can also be used by an oldersubject who may have less mobility and therefore uses a wheel chair asshown in FIG. 9.

Control Device for Generating Air-Pulse Trains

The electropneumatic device for controlling the air-pulse trains iscontrolled from a laptop computer via an I/O card (in/out card). Customsoftware controls the pulse train air or gas pressure throughelectropneumatic low air pressure regulators. Custom software alsocontrols air pulse duration, air pulse frequency, and train durationthrough in-line series solenoids. The pressurized air source is aportable air compressor. The I/O card, air pressure regulator, andsolenoids are housed together within a rigid plastic box that alsocontains all electrical circuitry.

The prescribed air-pulse trains from each of two solenoids flow alongrigid polyethylene tubing (preferably inner diameter (ID): 1.14 mm,outer diameter (OD): 1.57 mm). These two lines provided air-pulsesources to the right and left sides of the mouth. Temporal features ofthe right and left side air-pulse trains are controllable independentlyto allow for unilateral, or bilateral, stimulation. The tubing 14 entersthe subject's mouth within 1 cm of the subject's midline, passingbetween the subject's lips. The polyethylene tubing 14 is then embeddedwithin an ultra-thin (i.e., 1 mm) lower dental splint 12 made of dentalresin, as described above (see FIGS. 1 and 2).

Preferably the pneumatic system is calibrated immediately before eachtesting/intervention session with the portable manometer. The manometeralso allows for on-line verification of air-pulse pressure duringexperimental/therapeutic sessions.

Subjects

Four right-handed female volunteers with no history of swallowing,orofacial, gastrointestinal, respiratory, or neurological problems wererecruited as subjects (age, 30±10.8 yr, mean±SD). A lower dental splintwas custom made for each subject.

Experimental Session

The experimental session was conducted in the Orofacial NeuroscienceLaboratory at the University of Western Ontario with the subjectcomfortably seated in a straight-backed chair. At the end of theexperimental session, the subject was asked to describe any sensationsassociated with the stimulation, as well as any responses to thestimulation.

Identification of Swallowing

Laryngeal and respiratory movements were continually recorded, using adigital data acquisition system, throughout the experimental sessionfrom the output signals of pressure transducers driven from expandingbellows positioned comfortably around the subject's neck and around theribcage, respectively. Swallowing was identified on the basis of adistinct pattern of laryngeal movement in association with a transientrespiratory apnea (see FIGS. 12 and 13). The number of swallows thatoccurred within each 5-minute baseline or stimulation period wascalculated as the outcome variable for each subject. In addition, thelatency of each swallow was calculated relative to the onset of the10-second air-pulse train immediately preceding the swallow, using thepeak of the swallow-related laryngeal movement signal as the indicatorof swallowing. Mean swallow latencies were calculated for each subjectand for the group.

Task/Stimulation Paradigm

The effects of four air-pulse stimulation conditions on swallowingfrequency were examined: right-sided oropharyngeal air-pulsestimulation, left-sided oropharyngeal air-pulse stimulation, bilateraloropharyngeal air-pulse stimulation, and, as a control, unilateralair-pulse stimulation of the dominant (right) hand. Across subjects, theorder of the stimulation conditions was randomized; the subjects wereblind with regard to the randomization order and were informed only thatair-pulse stimulation might be applied either to the mouth or the hand.At the beginning of the experimental session, an adaptation period of 30minutes provided an opportunity for the subject to adjust to the dentalsplint. Thereafter, the subject wore the splint throughout the entireexperimental session.

During the experimental session, resting laryngeal and respiratorymovement data were collected during four 5-minute baseline periods, twoimmediately preceding, and two immediately following the air-pulsestimulation periods (see FIG. 14). There were four 5-minute air-pulsestimulation periods. Within each of these air-pulse stimulation periods,a total of six 10-second air-pulse trains (repetition frequency=2 Hz,air pressure=6-8 cm H₂O) were alternated with stimulation-free periodsthat varied in duration from 25 to 58 seconds.

Statistical Analysis

Nonparametric statistics were applied based on the small sample size andthe nonrandom selection of subjects. A Wilcoxon signed-ranks procedurewas used to test for significant differences in the number of swallowsproduced during (a) the two pre-stimulation baseline periods, (b) thetwo post-stimulation baseline periods, as well as (c) thepre-stimulation and post-stimulation baseline periods. A Friedmantwo-way analysis of variance (ANOVA) by ranks, with repeated measures(Factor A=air-pulse stimulation, Factor B=time) was used to examine theeffect of air-pulse stimulation on evoked swallowing. The outcomes ofmultiple pairwise comparisons were judged against a minimum significantdifference (MSD) value to determine significant differences betweenpairs of stimulation conditions. The MSD value was calculated asfollows:

MSD=z*√([number of subjects][number of conditions][number ofconditions+1])/6, where z is a critical value chosen based on thefamily-wise error rate (α_(FW)) and the number of comparisons being made

Results Subjective Reports

All subjects reported an irrepressible urge to swallow in response tothe oropharyngeal air-pulse stimulation, particularly during thebilateral stimulation condition, followed by an overt swallow asverified by laryngeal and respiratory movements. The stimulus wasperceived as contacting the peritonsillar region in all cases. Somesubjects described the air-pulse trains as cool in relation to thetemperature of the mouth. Some noted that the air-pulse trains increasedthe total volume of air within the oropharyngeal cavity.

Swallowing Frequency

The mean number of swallows produced during the two pre-stimulationbaseline periods, as well as the two post-stimulation periods, were notsignificantly different (Wilcoxon signed ranks test, p<0.05). Therefore,the data from the two pre-stimulation baseline periods and from the twopost-stimulation baseline periods were averaged to obtain a singlepre-stimulation baseline period and a single post-stimulation baselineperiod, respectively, for each subject. Similarly, the numbers ofswallows produced during the pre-stimulation and post-stimulationbaseline periods were not significantly different and, thus these werealso averaged in subsequent analyses. These findings suggest that, byincorporating the 30-minute splint habituation period, a stableswallowing baseline was achieved prior to the oropharyngeal stimulationconditions.

There was a significant main effect of air-pulse stimulation on swallowfrequency (Freidman two-way ANOVA by ranks, p<0.05; FIGS. 15, 16).Multiple pairwise comparisons (MSD=13.1; A_(FW)=0.10, 15 pairwisecomparisons; one-tailed z=2.475, indicated that swallowing frequency wassignificantly greater during right oropharyngeal stimulation (9.75±4.43SD) than during hand stimulation (2.75±1.89 SD), and during bilateraloropharyngeal stimulation (11.75±6.6 SD) compared to hand stimulation.The comparison of bilateral oropharyngeal stimulation and the baseline(4.31±0.88 SD) approached significance. Thus, air-pulse stimulation wasassociated with a significant increase in swallowing frequency.

Results from a similar study with a subject who had suffered a strokeare shown in FIG. 17. Oropharyngeal air-pulse stimulation was associatedwith a clear increase in swallowing frequency, relative to baselinelevels. Thus, a similar effect of the air-pulse application was seen inboth the healthy subjects and the subjects with stroke. This suggeststhat the air-pulse approach may have therapeutic utility in patientswith swallowing impairment who have difficulty triggering a swallow.This may include not only persons who have suffered a stroke but alsopersons who have undergone resection and/or chemoradiation for cancer ofthe head or neck, persons with various neurological conditions such ascerebral palsy, and Parkinson's disease, or those recovering fromtraumatic brain injuries.

Swallowing Latencies

The mean swallowing response latencies associated with the bilateraloropharyngeal stimulation tended to be less than the latencies ofswallows following unilateral oropharyngeal stimulation (see Table 1).Across subjects and swallowing trials, the swallow latencies ranged from2.8 to 39.3 seconds. In general, subjects with greater total numbers ofswallows per stimulation block demonstrated shorter swallow latencies.

TABLE 1 Mean swallowing response latencies (seconds; mean ± SD) relativeto onset of 10-second air-pulse trains for left unilateral, rightunilateral and bilateral oropharyngeal stimulation. Stimulation Subject1 Subject 2 Subject 3 Subject 4 Group Unilateral 12.02 (±15.55) 7.57(±2.16) 22.28 (±6.64) 15.34 (±3.08) 13.57 (±9.48)  Left (n = 5) (n = 6)(n = 4) (n = 5) (n = 20) Unilateral 11.42 (±7.52)   5.3 (±1.79) 19.05(±6.59)  10.48 (±(2.48) 10.9 (±6.74) Right (n = 6) (n = 6) (n = 4) (n =5) (n = 21) Bilateral 6.77 (±2.94) 4.92 (±1.31)  23.83 (±10.35)  9.0(±5.08) 9.31 (±7.69) (n = 6) (n = 6) (n = 3) (n = 6) (n = 21) (n =number of swallows that occurred during each stimulation condition).

Discussion

Accordingly stimulation of the human oropharynx with air-pulse trainsfacilitates swallowing, particularly when the stimulation is appliedbilaterally. This finding provides support for the widely held view thatoropharyngeal sensory stimulation plays an important role in swallowinginitiation. It also suggests that oropharyngeal air-pulse stimulationmay hold therapeutic potential for some individuals who suffer fromdysphagia.

Subjective Reports

All the subjects in the present investigation reported that theair-pulse stimulation evoked a strong, irrepressible urge to swallow.This finding is in contrast to previous investigations that employedother oropharyngeal stimuli and found only a modest swallowing urgeaccompanied by infrequent swallowing elicitation. The strong urge toswallow documented suggests that the oropharyngeal air-pulse train maybe a particularly potent stimulus for evoking swallowing.

The air-pulse trains were perceived by the subjects as evoking a numberof oropharyngeal sensations. These included dynamic touch, pressure, andcool temperature. These subjective reports beg the question of whatspecific attribute(s) of the air-pulse stimulation facilitatedswallowing. The peritonsillar area is richly endowed with a variety ofsensory receptors including mechanoreceptors and thermoreceptors. Theair-pulse train would be expected to excite low-threshold oropharyngealmechanoreceptors, including those sensitive to moving stimuli. Inaddition, given that some subjects perceived the air-pulse trains ascool, it is possible that the oropharyngeal thermoreceptors were alsoexcited. Future studies in which properties of the stimulus areindependently manipulated are required to clarify the essentialproperties of the air-pulse trains in eliciting swallowing.

The mechanism through which the air-pulse trains facilitated swallowingshould be explored. Local circuits involving GPN and SLN afferent inputsto the medullary swallow center and cranial nerve outputs to the upperaerodigestive tract musculature (3, 31) may mediate the facilitatoryeffect of the peritonsillar air-pulse stimulation on swallowing. Theobserved trend that bilateral stimulation was associated with greaterswallowing facilitation than unilateral stimulation suggests that anadditive mechanism is involved in which sensory inputs from the twosides of the oropharynx summate in initiating swallowing. However, otherpossible mechanisms are also worth considering. Cortical mechanismspreviously implicated in swallowing initiation and control may havecontributed to the observed facilitation of swallowing. In addition, anattentional mechanism may have played a role, particularly since thestimulation was suprathreshold. It is noteworthy that the swallowingfrequency in the hand condition was slightly less than that during thebaseline, suggesting the possibility that attention focused on thesensory stimulation of the hand region had an inhibitory effect onswallowing. Finally, it is possible that the air-pulse trains evoked asecretomotor response resulting in increased salivary flow during thestimulation. While this cannot be ruled out, it would seem unlikely thatincreased salivary flow would account for the swallows evoked atshortest latency, some of which occurred 2 sec following the stimulationonset. The potential influence of salivation should be examined infuture studies.

Limitations

The initial study was preliminary in nature and examined a small sampleof subjects. It is likely that intersubject variability within thissmall sample contributed to the variable results of the plannedcomparisons, masking some treatment effects. Nevertheless, a significantmain effect of air-pulse stimulation found within this limited samplesuggests that the facilitatory effect of the oropharyngeal air-pulsetrains on swallowing is quite robust.

Other aspects of the methodology also may have influenced the observedeffects of the air-pulse stimulation. For example, neither the subjectsnor the experimenters were naive to the focus of the study or theexperimental stimulation conditions. Because the stimulation wassuprathreshold, the subjects were aware of the stimulation time-course.In addition, the stimulation was controlled by a manually operatedpneumatic system that may have introduced variability in the amplitudeand duration of the air-pulse trains. Replication studies with blindingof experimenters and subjects, and computer-controlled air-pulse trainsare necessary to confirm the present findings.

Clinical Applications

Oropharyngeal sensory stimulation has been advocated as a means offacilitating swallowing in patients suffering from dysphagia. A numberof approaches to oropharyngeal stimulation have been reported includingmanipulating properties of the bolus (e.g., sour bolus, chilled bolus),as well as direct mechanical, thermomechanical, or electricalstimulation applied to the anterior tonsillar pillars or palate. Theseapproaches have achieved substantial clinical acceptance in spite of thefact their efficacy has been difficult to establish. For example, whilesome authors have reported that cold mechanical stimulation of theanterior tonsillar pillar decreases swallowing latency and increasesswallowing frequency, others have failed to find an effect of this typeof stimulation on oropharyngeal bolus transit, esophageal coordination,or the temporal pattern of swallowing. Similarly, whereas some authorshave reported that swallowing latency is significantly reduced by acombination of mechanical, cold, and gustatory (sour) stimulation,others have reported that a cold plus sour bolus reduces the speed ofswallowing. Four studies have examined oropharyngeal sensorymanipulations in dysphagic patients following stroke patients. A sourbolus has been reported to facilitate swallowing in stroke. Threestudies have examined the effects of cold mechanical stimulation appliedto the anterior tonsillar pillars in small samples of dysphagic strokepatients. They reported a short-term facilitation of swallowing,measured in terms of reduced delay of the pharyngeal swallow, in somepatients, with no related reduction in aspiration. Longitudinal studies,examining the potential long-term effects of oropharyngealsensitization, have not been reported.

The present finding that air-pulse trains delivered to the peritonsillarregion of the oropharynx are associated with a strong urge to swallow,and a significant increase in swallowing frequency, suggests thatoropharyngeal air-pulse stimulation may hold therapeutic potential forsome individuals who suffer from dysphagia, including dysphagicindividuals who experience delayed triggering of the swallow reflex.Oropharyngeal air-pulse stimulation may be particularly appropriate forindividuals who present with an oropharyngeal sensory deficit and/ordelayed pharyngeal swallow, for example, secondary to stroke. Theinventors' current studies are addressing this exciting clinicalquestion.

It will be appreciated by those skilled in the art that the splint ofthe present invention could also be used as a diagnostic device. As adiagnostic tool a single or train of air pulses may be used. Thelocation of the air pulse would be determined by the diagnostician. Somelocations could be the peri-tonsillar area, the roof of the mouth orpalate, or the tongue. The air pulse may be just on one or the otherside of the mouth or both sides of the mouth. Air was used herein,however other gases may be used and may be particularly desirable wherespecific temperatures are required.

It will be appreciated by those skilled in the art that there are fewtherapies available for individuals with speech and swallowingimpairment. The oral device of the present invention delivers calibratedvolumes of air to the mouth, that is, an air “bolus”. The air bolusincreases oral pressure. It has been shown, in healthy controls and inpatients with stroke, that air bolus delivery elicits elevationmovements of the larynx. Because laryngeal elevation is a centralcomponent of swallowing, swallowing can also be elicited as a derivativeof the laryngeal elevation. The oral air bolus also appears to increasespeech intelligibility, lip strength, and soft palate strength inpatients following stroke. The oropharyngeal air-pulse application alsoincreases salivary flow in some patients following stroke. Thus, theoral device of the present invention may also be used to increase salivaproduction in patients with reduced salivary flow, for example, inpatients who have undergone radiation therapy involving the salivaryglands in the field of radiation. Accordingly, the oral device of thepresent invention may also be used for both swallowing therapy andspeech therapy.

As used herein, the terms “comprises” and “comprising” are to beconstrued as being inclusive and open rather than exclusive.Specifically, when used in this specification including the claims, theterms “comprises” and “comprising” and variations thereof mean that thespecified features, steps or components are included. The terms are notto be interpreted to exclude the presence of other features, steps orcomponents.

It will be appreciated that the above description is related to theinvention by way of example only. Many variations on the invention willbe obvious to those skilled in the art and such obvious variations arewithin the scope of the invention as described herein whether or notexpressly described.

1-65. (canceled)
 66. An oral device for use in a subject's mouth, theoral device comprising; first and second laterally spaced conduits fordelivering at least one gas pulse to a predetermined location in thesubject's mouth, wherein the laterally spaced first and second conduitsdefine a central opening therebetween such that the first and secondconduits are not disposed between the subject's tongue and a roof of thesubject's mouth, wherein the tongue is free to touch the roof of themouth when the first and second conduits are positioned in the subject'smouth; and a gas pulse generator transmitting the at least one gas pulsethrough at least one of the first and second conduits.
 67. An oraldevice as claimed in claim 66 further comprising a dental splintcomprising the first and second conduits.
 68. An oral device as claimedin claim 66 wherein each of the first and second conduits has a gas exitopening at the distal end thereof.
 69. An oral device as claimed inclaim 66 wherein each of the first and second conduits has a pluralityof gas exit openings formed therein.
 70. An oral device as claimed inclaim 66 further comprising a control system for controlling parametersof the transmission of the at least one gas pulse.
 71. An oral device asclaimed in claim 70 wherein the control system controls a pressure ofthe at least one gas pulse.
 72. An oral device as claimed in claim 71wherein the at least one gas pulse comprises a train of gas pulses, andwherein the control system further controls at least one of a frequencyand duration of the gas pulses in the train.
 73. An oral device asclaimed in claim 70 wherein the control system separately controls theparameters of the transmission of the at least one gas pulse in each ofthe first and second conduits.
 74. An oral device as claimed in claim 66wherein the gas is air.
 75. An oral device as claimed in claim 66wherein at least one of the first and second conduits has a gas exitopening directed rearwardly wherein the predetermined location is aperi-tonsillar area of the mouth.
 76. An oral device as claimed in claim66 wherein at least one of the first and second conduits has a gas exitopening directed upwardly wherein the predetermined location is a roofof the mouth.
 77. An oral device as claimed in claim 66 wherein at leastone of the first and second conduits has a gas exit opening directedinwardly wherein the predetermined location is a tongue area of themouth.
 78. An oral device as claimed in claim 66 wherein the gas pulsegenerator comprises a portable air compressor.
 79. An oral device asclaimed in claim 70 wherein the control system comprises an air pressureregulator and a solenoid.
 80. An oral device as claimed in claim 66wherein the at least one gas pulse comprises a train of pulses.
 81. Anoral device as claimed in claim 80 wherein the pulse frequency of thetrain of pulses is between 0.5 and 30 Hz.
 82. An oral device as claimedin claim 80 wherein the train of pulses has a duration of between 2 and20 seconds.
 83. An oral device as claimed in claim 66 wherein thepressure of the at least one gas pulse is between 3 cm water and 15 cmwater.
 84. An oral device as claimed in claim 66 wherein across-sectional thickness of the first and second conduits, the spacingbetween the first and second conduits and a width of the central openingare dimensioned such that any spacing between the subject's jaws is nomore than a just noticeable difference for jaw position.
 85. An oraldevice as claimed in claim 85 wherein the spacing between the subject'sjaws is less than 2 mm.
 86. The oral device as claimed in claim 86wherein the spacing is between 1 and 2 mm.
 87. An oral device for use ina subject's mouth, the oral device comprising; at least one conduitadapted to deliver at least one gas pulse to a predetermined location ina subject's mouth to induce swallowing while at least a portion of theconduit remains in the subject's mouth; and a gas pulse generatortransmitting the at least one gas pulse through the at least oneconduit.
 88. An oral device as claimed in claim 66 wherein the at leastone conduit comprises a pair of laterally spaced conduits.
 89. An oraldevice as claimed in claim 87 wherein the at least one conduit has a gasexit opening.
 90. An oral device as claimed in claim 87 wherein the atleast one conduit has a plurality of gas exit openings formed therein.91. An oral device as claimed in claim 87 further comprising a controlsystem for controlling parameters of the transmission of the at leastone gas pulse.
 92. An oral device as claimed in claim 91 wherein the atleast one gas pulse comprises a train of gas pulses, and wherein theparameters include at least one of a pressure, a duration and afrequency.
 93. An oral device as claimed in claim 87 wherein the atleast one conduit has a gas exit opening directed rearwardly wherein thepredetermined location is a peri-tonsillar area of the mouth.
 94. Anoral device as claimed in claim 87 wherein the at least one conduit hasa gas exit opening directed upwardly wherein the predetermined locationis a roof of the mouth.
 95. An oral device as claimed in claim 87wherein the at least one conduit has a gas exit opening directedinwardly wherein the predetermined location is a tongue area of themouth.
 96. An oral device as claimed in claim 92 wherein the pulsefrequency of the train of pulses is between 0.5 and 30 Hz.
 97. An oraldevice as claimed in claim 92 wherein the train of pulses has a durationof between 2 and 20 seconds.
 98. An oral device as claimed in claim 92wherein the pressure of the train of gas pulses is between 3 cm waterand 15 cm water.